1. Field of the Invention
The invention relates to an arrangement for the generation of a trigger pulse for the ignition of fuel in an internal-combustion engine, the trigger pulse being generated with a preset crankshaft angular position, related to a reference angle position.
2. Description of the Prior Art
The peak pressure in the combustion chamber of an internal-combustion engine must be reached in a determined position of the piston or in a determined crankshaft angular position, respectively, related to a reference angle position, normally related to the upper dead center, so that the efficiency of the engine is optimal. Due to the finite velocity of combustion within the ignited air-fuel mixture it is necessary to advance the ignition pulse in regard to the upper dead center with increasing speed. For this a large number of mechanical, electronical-analog, and digital ignition systems are known.
The velocity of combustion of the air-fuel mixture inter alia depends also on the filling of the combustion chamber so that in the part-load range the velocity of combustion decreases due to the reduced filling. Consequently the trigger pulse is shifted to an advanced angle value by means of pressure sensors. By this technique a shifting of the ignititon pulse is possible only as a function of parameters, which are preprogrammed. Variations of further operational conditions, such as fuel quality, air temperature, engine temperature, practically cannot be detected due the fact that a sensory system necessary is too complicated and expensive in practice.